Background: The aim of our study was to elucidate the association of the metabolic syndrome with the risk of unsuccessful pregnancy. Methods: This was a retrospective observational study conducted at Markusovszky Teaching Hospital, Szombathely, Hungary, a tertiary health care center. During the study period of 2007-2011 (5 years), 7373 pregnancies were followed. Pregnant women who were suffering from metabolic syndrome in the first trimester of gestation during the study period were compared to all other pregnant women without the syndrome. Retrospectively, 219 (2.9%) patients met the criteria of metabolic syndrome during the first trimester. Our goal was to evaluate the prevalence of the metabolic syndrome in normal pregnancies and in those complicated by either premature birth, or intrauterine growth retardation (IUGR), pregnancy-induced hypertension, and preeclampsia. Results: The rate of preterm birth was 15.2% [32/219 in the metabolic syndrome group vs. 11.1% (p = 0.051) in the control group]. Within the affected group, 40 pregnancies were complicated with IUGR (18.4%) versus 3.3%, in the unaffected group (p < 0.001). In 58 cases, we observed preeclampsia during pregnancy [26.7% vs. 5.2% (p < 0.001)] in the control group. Among the patients affected by the metabolic syndrome, 83 patients (38.2%) had more then one pregnancy complication during pregnancy, and only 59 cases (27.2%) had no adverse events during pregnancy and delivery (p < 0.001). Conclusions: Our study demonstrated a higher rate of complicated pregnancies in association with metabolic syndrome compared to the control group.